Update version number of WECCA to be installed under R-3.0 and prune outdated.

- Update the version number of package WECCA to be installed under R-3.0.
- Remove CGHcallPlus.R files from common/R-2.12 and common/R-2.15 (no tools use these files anymore).
- Remove packages CGHregions, CGHcall, CGHbase, GOstats, and impute from being installed under R-2.15 as they are not used anymore.